System and Method for Enforcing Policy in a Communication Network

ABSTRACT

A system for enforcing policy in a communication network includes a policy server which is operable to receive a request to invoke an application, receive a policy profile for a network user, and decide a proper allocation of network users based on the policy profile, the application, and available network resources. The policy server is further operable to communicate with a non-SIP application. The system also includes a network resource manager operably associated with the policy server and operable to monitor available network in the resources in the communication network. In addition, the network resource manager is functional to allocate network resource amongst a plurality of network users. The system also contains an application control point which is operably associated with the policy server and operable to communicate with a SIP application. The system is operable to use policy peering between the home and visited network to enable user-specific policies to be enforced while roaming.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/771,513 filed Feb. 7, 2006.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to communication systems and moreparticularly to a system and method for enforcing policy in acommunication network.

BACKGROUND OF THE INVENTION

As communication services and products continue to grow and expand, sodoes the need to enforce policy within a communication network. Whileapplications such as push-to-talk, video-telephony, and enterprise videoconferencing have enhanced communications, they necessitate a broaderrange of policy enforcement capabilities. In particular, because suchapplications may operate using Session Initiation Protocol (SIP), theyrequire unique interfaces between network devices to enforce policy.Further complicating policy enforcement is the need to provideuser-specific policies since every subscriber is not the same and somewill pay more for their services than others. Enforcing a user-specificpolicy in a modern communications environment wherein a user may roambetween networks hosted by different providers also presents apredicament as the user's policy profile is typically only stored by thehome service provider.

The IP Multimedia Subsystem (IMS) is a next generation networkingarchitecture that allows service providers to provide both mobile andfixed multimedia services. Because IMS runs over the Internet protocol(IP) it allows a service provider to provide any service which theInternet can or will support. While the IMS architecture has numerousbenefits, it currently only supports SIP enabled devices. Accordingly,it is not able to provide roaming policy support for many legacy devicesand applications that do not use SIP. Further, the range of policycontrol which the system provides is limited to Quality of Service (QoS)and accounting. Given the breadth of features and the range of networkresources necessary to support such features, it is desirable to enablea broader range of policy control.

SUMMARY OF THE INVENTION

In accordance with the present invention, a system and method forenforcing policy in a communication network is provided whichsubstantially eliminates or reduces the disadvantages and problemsassociated with previous systems and methods.

In accordance with a particular embodiment of the present invention, asystem for enforcing policy in a communication network includes a policyserver which is operable to receive both an authorization request toallow an application invocation and a policy profile for a network user,and then decide a proper allocation of network resources based on thepolicy profile, the application, and available network resources.Network resources is here extended to not only include the traditionalQuality of Service and associated accounting, but to also includenetwork services such as security services, mobility services, relayservices, transcoding functions, packet replication services, and deeppacket inspection services. The policy server is further operable tocommunicate with a non-SIP application. The system also includes anetwork resource manager associated with the policy server and operableto monitor available network resources in the communication network. Inaddition, the network resource manager is functional to allocate networkresources amongst a plurality of network users. The system also containsan application control point which is associated with the policy serverand operable to communicate with a SIP application.

In more particular embodiments, the policy server may also decidewhether an application may be invoked based on the application, a policyprofile, and available network resources and communicate the decision tothe application control point. In another embodiment, the authorizationrequest comprises at least one token representing the application, andzero or more tokens representing altered application behavior, e.g.lowered bit-rate for a video stream. In yet another embodiment, theapplication control point is operable to invoke a different applicationbased on the allocation of available network resources, or to alter theapplication behavior based on the allocation of available networkresources.

In accordance with another embodiment of the present invention, a methodfor enforcing policy in a communication network includes sending arequest to invoke an application from an access terminal, and sending apolicy authorization request for the application invocation to a policyserver in response to receiving the request to invoke. In thisembodiment, the authorization contains a set of tokens representing theapplication and its associated parameters, e.g. media streams withassociated media types, codecs and bandwidth requirements. The methodalso includes obtaining a policy profile and information regardingavailable network resources from a network resource manager. The methodfurther includes allocating available network resources based on thepolicy profile, the application tokens, and the available networkresources. The method also includes the policy server possibly modifyingthe application invocation by passing a set of tokens back to therequesting application.

Technical advantages of particular embodiments of the present inventioninclude enabling policy enforcement for SIP and non-SIP applications anddevices in both visited and home networks. Another technical advantageis that the policy server is functional to enforce policy over amultitude of network resources, not simply QoS and accounting. A furtheradvantage is that applications and their associated parameters may berepresented by tokens which allows for applications to be added,modified and controlled without changing the software in deployedcomponents. Also, the policy server may influence the applicationbehavior by sending tokens to the application.

Other technical advantages will be readily apparent to one skilled inthe art from the following figures, descriptions, and claims. Moreover,while specific advantages have been enumerated above, variousembodiments may include all, some or none of the enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

To provide a more complete understanding of the present invention andthe features and advantages thereof, reference is made to the followingdescription, taken in conjunction with the accompanying drawings, inwhich like reference numerals indicate like features and wherein:

FIG. 1 is a simplified block diagram that illustrates a communicationsystem for enforcing policy in a communication network;

FIG. 2 is a simplified block diagram that illustrates a split policyenforcement model of the communication system;

FIG. 3 is a simplified block diagram that illustrates the operation ofthe communication system; and

FIG. 4 is a simplified block diagram that illustrates policy peering inthe communication system.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a communication system 10 for communicating,receiving, and/or transmitting data in accordance with an embodiment ofthe present invention. Communication system 10 includes a plurality ofaccess terminals 12, communication network 22, and external multimediadomain (MMD) 26. Communication system 10 further includes policy center30 which comprises policy server 32, application control point 34,network resource manager 36, Services Data Management Center (SDMC) 38,and Security Center Server (SCS) 39. Also included in communicationsystem 10 is application server 40 which may include Session InitiationProtocol (SIP) applications 42 and non-SIP applications 44.

In accordance with the teachings of the present invention, policy center30 is functional to apply subscriber specific system policies acrosscommunication system 10. In another embodiment of the present invention,policy center 30 is further capable of applying generic network policythroughout communication system 10. Further, policy center 30 may alsoapply such policies to both SIP and non-SIP based applications as wellas roaming and non-roaming subscribers.

As illustrated in FIG. 1, communication network 22 represents a seriesof points or nodes of interconnected communication paths for receivingand transmitting information or data throughout communication system 10.While illustrated as a single network, communication network 22 isintended to represent any number, type, size, or group of communicationnetworks. More particularly, communication network 22 represents anynetwork, or group of networks, capable of transmitting audio, and/orvideo telecommunication signals, data, and/or messages, includingsignals, data, or messages transmitted through text chat, instantmessaging, and e-mail. In particular, a communication network maycomprise all or a portion of a radio access network, a public switchedtelephone network (PSTN), a public or private data network, a local areanetwork (LAN), a metropolitan area network (MAN), a wide area network(WAN), a local, regional, or global communication or computer networksuch as the Internet, a wireline or wireless network, an enterpriseintranet, other suitable communication link, or any combination of thepreceding.

Communication network 22 may contain or interface with any combinationof hardware and/or software to provide its intended communicationcapabilities. For example, communication network 22 may contain anynumber or combination of communication platforms, routers, servers,gateways, switches, hubs, and/or conference bridges. In certainembodiments, communication network 22 may also contain any number ofapplication specific integrated circuits (ASIC), processors,microprocessors, algorithms, read-only memory (ROM) elements, randomaccess memory (RAM) elements, erasable programmable ROM (EPROM),electrically erasable programmable ROM (EEPROM), field-programmable gatearray (FPGA), or any other suitable element or object that is operableto facilitate the operations thereof.

In particular embodiments of the present invention, communicationnetwork 22 implements a TCP/IP communication protocol. However,communication network 22 may implement any other suitable communicationprotocol for transmitting and receiving data packets withincommunication system 10. Using Internet Protocol (IP), each of thecomponents coupled together by communication network 22 in communicationsystem 10 may be identified in information directed using IP addresses.In this manner, communication network may support any form and/orcombination of point-to-point, multicast, unicast or other techniquesfor exchanging media packets or information among components incommunication system 10. In another embodiment of the present invention,communication network 22 may receive and transmit data in a SessionInitiation Protocol (SIP) environment. SIP is an application-layercontrol protocol that includes primitives for establishing, modifying,and terminating communication sessions. SIP works independently ofunderlying transport protocols and without dependency on the type ofsession that is being established. In further embodiments, components ofcommunication network 22 may use various other protocols andtechnologies, including but not limited to global system for mobilecommunications (GSM), code division multiple access (CDMA), and anyother appropriate analog or digital wireless protocol or technology.

External MMD 26 represents a communications network controlled by adifferent service provider than the rest of communication system 10.Accordingly, external MMD 26 may represent a roaming or visited network.In one embodiment of the present invention, external MMD 26 is a networkcontaining the policy center 30 architecture of communication system 10.External MMD 26 may also be an IP Multimedia Subsystem (IMS) network orany other combination of devices for transmitting and receiving data andinformation. Further, external MMD 26 may be equipped with anycombination of devices or features provided for in communication network22.

Access terminals 12 are the objects upon which user-specific systempolicy is enforced. Access terminals 12 may encompass a myriad ofpotential devices and infrastructure that may benefit from the operationof communication system 10. For example, an access terminal may includea Personal Digital Assistant (PDA), a cellular telephone, a standardtelephone, an IP telephone, a personal computer, a mobile telephone, orany other suitable device that is operable to receive or transmit data.Each access terminal may also include suitable network equipment andappropriate infrastructure such as switches, routers, LANs, or gatewaysto facilitate a communication session within communication system 10.Further, in particular embodiments, access terminals 12 may be SIPcompatible elements.

Access terminals 12 may connect to a communication network in numerousways. For instance, a connection might be made through a fixed broadbandconnection such as a digital subscriber line (DSL), cable modem, orEthernet. Wireless access to communication network 22 may be initiatedthrough a WLAN, WiMAX, or WiFi access point. Further, mobile access maybe permitted via CDMA, CDMA 2000, GSM, UMTS, or any other mobilestandard. Although FIG. 1 illustrates a particular number andconfiguration of access terminals 12, communication system 10contemplates any number or arrangement of such components.

Application server 40 hosts and executes applications. The termapplication refers generally to any services that a subscriber might seeand use. In particular, applications may include push to talk overcellular (PoC), basic voice service, video-telephony, streaming movies,enterprise voice conferencing, voicemail and so on. In certainembodiments, the applications are SIP applications 44 and/or non-SIPapplications 44. In addition to applications, application server 40 mayalso include a media server 46 for transmitting various video, audio,and other data.

Policy center 30 implements and deploys policies throughoutcommunication system 10. While the illustrated embodiment indicates thatpolicy center 30 comprises policy server 32, ACP 34, network resourcemanager 36, SDMC 38, and security center 39, policy center 30 mayinclude any combination of elements operable to enforce policy in acommunications network. Further, one skilled in the art will readilyrecognize that the components of policy center 30 may be combined in anysuitable manner without departing from the scope of the presentinvention.

Policies might include which applications a user may run, when anapplication may be run, how network resources are allocated to anapplication or user, and any other decision that affects networkresources or user interaction within a communication network. Moreover,a policy might be user-specific or generic to all users of communicationsystem 10. For example, a user-specific policy might provide that aparticular user may use certain applications. By contrast, a genericpolicy might require that a certain percentage of network bandwidth beallocated to streaming media. Enforcing both generic and user-specificpolicies enables a service provider to efficiently allocate resourceswithin a communication network while simultaneously providing for theunique needs of an individual user.

In an embodiment of the present invention, policy center 30 allocatesnetwork resources by application, and possibly associated applicationparameters, as opposed to application independent criteria such asbandwidth. This is done for all kinds of applications, both SIP andnon-SIP based. Because users often purchase applications (as opposed tosimply bandwidth), a subscriber does not care how much bandwidth anapplication requires, rather that the application is functional.Therefore, allocating network resources according to applications mayallow a service provider to better serve its users.

Policy center 30 is also functional to dynamically adjust policydecisions based on changes to network properties. Because networkresources constantly fluctuate, it is desirable to provide flexiblepolicy enforcement. For example, if a user enters a poor coverage areawhile simultaneously running a video-telephony session and a multimediagame, policy center 30 might provide the user with a pop-up messageinforming the user that one of the two applications has been disabled.Alternatively, the message may query the user to elect which of the twoapplications to disable.

Another feature of policy center 30 is that it may provide user-specificpolicy for all applications and all users. Accordingly, unlike a P-CSCFand its associated Policy and Charging Rules Function (PCRF) in an IMSnetwork, policy center 30 may assert policies for non-SIP applications.Further, by peering policy servers in various networks, a policy centerin a visited network can assert user-specific policies from the homenetwork of a roaming user, irrespective of whether the application usesSIP or not.

A further feature of policy center 30 is that it may implement anenhanced range of policies. While policy enforcement in networks such asthe IP Multimedia Subsystem (IMS) is typically limited to accounting andQoS, policy center is operable to enforce policy for security, mobility,relay, transcoding, packet replication, and deep packet inspection. Thebroader range of policy enforcement gives a service provider greatercontrol over its network, while enhancing user customization.

In the illustrated embodiment, the components of policy center 30 maycommunicate amongst each other via DIAMETER interfaces. Uniformcommunication interfaces promotes interoperability and enables policyenforcement to be applied to applications invoked by differentprotocols. The DIAMETER protocol is a derivation from the RemoteAuthentication Dial In User Service (RADIUS) protocol which enables userAuthentication, Authorization, and Accounting (AAA) services. Becauseauthentication and authorization mechanisms vary according toapplication, DIAMETER applications are able to define their own messagesand corresponding attributes. Accordingly, the DIAMETER protocol is nottied to a specific application running on top of it. Therefore, theDIAMETER protocol enables policy center 30 to implement network anduser-specific policy for both SIP and non-SIP applications.

Services Data Management Center SDMC 38 is the central data repositoryin communication system 10. SDMC 38 may store access terminal specificdata in addition to user specific data. Access terminal specific datamay include the access terminal profile and network policy data which isnot specific to any user. User specific data may include user policydata, user profile data (i.e. a user policy profile), and static userdata. Static user data comprises information that is necessary to beretained by service enablers and the application server for deployingapplications. In particular, static user data might include featureactivation status, buddy lists, or authorization rules. SDMC 38 may alsostore SIP routing information, charging information, and any otherrepository data that may need to be stored and retrieved in thecommunications network. As illustrated in FIG. 1, SDMC 38 interfaceswith policy server 32. This allows SDMC to pass updated policy profilesand other information so that current policy may be enforced.

Security Center Server (SCS) 39 handles security related functions forthe service provider within communication system 10. SCS may hold Layer2, Layer 3, and application layer authentication and encryption keys.SCS may also store all inter-network element encryption andauthentication keys. Further, SCS is functional to provide AAA servicesand information for devices and users within a communication system. Inparticular embodiments, SCS 39 may interface with policy server 32 andSDMC 38 to provide policy server 32 with a combined security and qualityof service (QoS) application policy.

Application Control Point 34 controls and manages SIP based multimediacommunications applications. More particularly, ACP is responsible forauthorizing SIP calls to and from access terminals and routing thosecalls to the proper terminating device whether it is another ACP, agateway to a PSTN, or an external MMD. Accordingly, ACP is similar tothe Call Session Control Function (CSCF) in an IMS communicationsnetwork.

In operation, ACP 34 interacts with SIP applications 44 and policyserver 32 to enforce policies at the applications layer. Because SIPapplications 44 do not directly interact with policy server 32, ACP 34requests authorization for invoking SIP applications from policy server32 which in turn makes a determination of what resources the applicationis authorized to use. Based on this determination, the ACP provides SIPapplications 44 with one or more service enablers to deploy theapplication. A service enabler might include user identity,registration, privacy, user security, presence, and location amongothers. Associated with each service enabler is a policy hook whichcontrols the operation of the application. Thus, ACP 34 is the policyenforcement point (PEP) at the applications layer for SIP basedapplications.

Network resource manager 36 is responsible for policy enforcement at thebearer or network level. Network level policy enforcement addresses hownetwork resources 50 are allocated to users within the network. Inparticular, network policies may include filtering packets, settingcounters, providing Quality of Service (QoS) and radio resources, andallocating bandwidth, among others, or any other decision regarding thedistribution of network resources.

Network resources 50 may include accounting, QoS, mobility, security,relay, transcoding, packet replication, and deep packet inspection.Accounting resources comprise packet counters and filters throughout thenetwork which may be configured to generate records to SDMC 38 forbilling purposes. The counters may also be configured with triggers toinform policy server 32 of specified occurrences. QoS refers toallocating bandwidth to control data flow in the network. Mobilityrelates to information regarding a user's communication session. Inparticular, such information may include duration of a networkconnection, the access network to which a user is connected, the user'ssignal strength, and the identity of the visited network (when roaming).Security relates to the identity of a network user, user authentication,and the relationship between user identity and operator policies. Relayreferences the allocation of network resource when a user connects to ahome network provider through an intermediary provider. Transcodingrefers to changing the encoding of media from one format to another.Packet replication refers to generating copies of packets (e.g.streams). Deep packet inspection refers to classifying network trafficbased on application layer information deep within a packet.

Network resource manager 36 also controls “over-the-top” applications48. Over-the-top applications are applications which have applicationservers that run outside of the service provider's network, but utilizenetwork resources. One type of over-the-top applications areapplications controlled by providers without a relationship to the homeservice provider. Such applications are referred to as “non-cooperative”over-the-top applications. Examples of such might include Skype orthird-party instant messaging programs such as AIM or Yahoo. Otherover-top-applications include applications in a home network invoked bya roaming user. If there is a business agreement between the homenetwork service provider and the roaming network service provider, thensuch applications are referred to as “cooperative” over-the-topapplications.

Because application servers for over-the-top applications do not havedirect interaction with the policy server in the accessed network, suchapplications are supported via deep packet inspection at deep packetinspector 52. Deep packet inspection services may operate at variouspoints in the network and function to classify network traffic accordingto application layer information deep within the packet.

Based on certain characteristics in the network traffic associated withthe over-the-top application, the policy server for the hosting networkmay implement certain policies. In particular, if the over-the-topapplication is cooperative, then the policy server might request thenetwork resource manager to allocate a certain bandwidth based on thebusiness relationship between the service providers. By contrast, if theapplication is a non-cooperative over-the-top application, the policyserver might request the network resource manager to provide reduced, oreven no, bandwidth at all for the application session. It should benoted that while the deep packet inspector is illustrated as a componentof network resource manager 36, deep packet inspector may be locatedanywhere in a communication network where it may provide its intendedfunctions.

As represented in FIG. 1, policy server 32 is the policy decision point(PDP) in policy center 30. As the PDP, policy server 32 is operable toreceive policy profiles and determine a proper allocation of networkresources and how applications should behave in light of the allocation.In particular, policy server 32 receives a user-specific or genericnetwork policy profile from an internal memory cache or SDMC and splitspolicy decisions into the appropriate parts for ACP 34 and networkresource manager 36 for application level and network level enforcement.

FIG. 2 illustrates the split policy enforcement model implementedthrough policy server 32 in accordance with an embodiment of the presentinvention. Because policy enforcement involves two sets of decisions theallocation of network resources to the application and applicationbehavior in view of the allocated resources it may be advantageous tosplit policy enforcement between signaling and network layers.

As illustrated in FIG. 2, policy server 32 receives a policy profile 33and outputs a decision as to how an application may use availablenetwork resources. The decision is enforced in different places. Networkresource manager 36 is the network layer policy enforcement point (PEP)and ACP is the PEP at the signaling layer. Accordingly, network resourcemanager might perform such tasks as filtering packets, setting counters,and providing QoS, whereas ACP might change which SIP applications areinvoked or terminate a call.

A split policy enforcement model offers several advantages. For example,having a single policy decision point allows for unified management ofapplications and network resources. This ensures that invokedapplications have sufficient resources and that applications are notdeployed without sufficient resources. Further, a split enforcementmodel enables policy peering wherein a home network may assert itspolicies when a user enters a roaming network, irrespective of whetherthe roamed-to network supports the application in question or not.Another benefit of the bifurcated approach is that policy may beenforced for both SIP and non-SIP applications. Specifically, ACP 34 isfunctional to interface with SIP applications and policy server 32 caninvoke non-SIP applications either directly or by communicating with anapplication server 40.

Returning again to FIG. 1, in an embodiment of the present invention,policy server 32 is linked to non-SIP applications 42 over a DIAMETERinterface. Non-SIP applications 42 comprise network applicationssupported by the home service provider which are not invoked using SIPprotocol. Such applications may include gaming and streaming media.Unlike SIP applications 44, for which ACP 34 is the application layerPEP, the PEP for non-SIP applications 42 is the non-SIP applicationitself. In either case however, the network level PEP is the networkresource manager. Accordingly, policy center 30 is functional to applynetwork and user policies to both SIP and non-SIP applications.

Policy server 32 may also interface with network resource manager 36.This connection permits policy server 32 to implement an array ofnetwork policies by linking it with network resources 50. For instance,mobility resources may allow for a mobility policy which defines whataccess networks a user may roam between (WiFi, WiMAX, CDMA, etc.).Similarly, a security policy might restrict which applications ornetwork resources a user might access. Further, the deep packetinspection resources could allow policy server to implement a policyregarding how the network should handle applications for which there isnot an application function. In particular, the policy server couldprovide that such applications can only be invoked in certain areas ofthe network or that the application be allotted reduced bandwidth. Theforegoing policies are provided as examples and should not restrict thescope of the invention as policy server 32 is operable to implement anynumber of policies regarding the allocation of network resources.

In a particular embodiment of the present invention, policy server 32 isoperable to store a copy of an active user's current policies andresource allocation in an internal memory cache. This information may beused to decide current capabilities and location of a user within thenetwork. Storing such information in an internal memory cache enhancesefficiency as the policy server 32 does not need to query SDMC 38 for anupdated policy-profile each time there is a change in available networkresources or a user invokes an application.

FIG. 3 illustrates the operation of policy center 30 in accordance withone embodiment of the present invention. As discussed, policyenforcement addresses both the allocation of network resources to anapplication and how an application behaves in view of the allocatedresources. Thus, policy control begins with the invocation of anapplication. An application is invoked by sending an invoke request 61to the application server 40 and/or ACP 34. While an application istypically invoked from an access terminal 12 (as illustrated in FIG. 3),applications may also be invoked by the network on the user's behalf.For instance, the network might send the user an alert for a calendarappointment or a user might receive a communication session request fromanother user.

An invoked application may be an over-the top application, a SIPapplication, and/or a non-SIP application. The means for invoking theapplication is application dependent. As an example, in the case of anapplication related to presence, instant messaging, or multimediacommunications, the invocation means is typically via SIP signaling. Inparticular, a video telephony application might be invoked with SIPINVITE messages and a presence subscription might be invoked by a SIPSUBSCRIBE message.

In response to receiving invoke request 61, application server 40 or ACP34 will send an authorization request 62 to policy server 32.Authorization request 62 is a message seeking authorization to launchthe invoked application with the parameters indicated. The request maycontain information regarding the application that is being invoked, itsassociated parameters and the network resources the application willrequire. In addition, authorization request 62 may include thesubscriber identity to allow policy server 32 to implement user-specificpolicies. It should be noted that, because ACP 34 serves as the PEP atthe application signaling layer, if the invoked application is SIPbased, then authorization request 62 is sent from the ACP.

In a particular embodiment of the present invention, authorizationrequest 62 may be in the form of one or more virtual token. A token is atext stream characterizing an invoked application and/or its associatedparameters. The characterization includes the requested media stream(s),but may also include other parameters relevant to support implementingpolicy while the application is deployed. In particular, the token mayinclude characterizations such as ‘voice’, ‘video’, ‘telephony’,‘interactive’, ‘Push-to-talk’, and ‘gaming’.

In an embodiment of the present invention, the token is created usingsyntactic processing pattern matching techniques which analyze thecontents of the application sought to be invoked. A pattern matchingtechnique might involve using a rules engine which performs matchingoperations between a set of input data (e.g. a SIP message) and a set ofmatching criteria (e.g. a message filter criterion) and decides if amatch exists. In response to a match, one or more tokens describing theapplication may be generated by either application server 40 or ACP 34.Once the rules engine has finished running through all of the applicableclassification rules, the resulting tokens are passed to policy server32 via authorization request 62. In addition to tokens, the message maycontain information regarding the invoke message such as the IP addressand ports for the media streams, the codecs, and the necessary bandwidthfor the codecs.

Classifying applications as tokens offers several advantages. Forinstance, using a token to characterize an application allows for newapplications to be added and controlled without requiring a softwareupgrade in the policy server. Specifically, because applications arerepresented as tokens, new ones can be added and policy can beimplemented for them without requiring significant networkmodifications. A further advantage is that, because a software upgradeis unnecessary, deployment time for a new application is reduced.

Returning to FIG. 3, in response to receiving authorization request 62,policy server 32 will obtain the user specific and/or network policyprofile. In an embodiment of the present invention, the profile may bestored locally in an internal memory cache within policy server 32 or inSDMC 38. Accordingly, policy server 32 will query its memory cache todetermine whether the policy profile for the user is available. If thepolicy profile is not stored locally, policy server 32 will obtain thepolicy profile from SDMC 38 through policy message 63.

After obtaining the policy profile, policy server 32 makes a policydecision regarding the invoked application. This decision may be basedon the contents of the token(s) in authorization request 62, the user'spolicy profile, the network's generic policy requirements, and/or theavailable network resources. The decision may be a “yes” or “no” answer.Alternatively, the decision may also be that the application mayproceed, but with reduced or limited functionality. For example, a usermight request to enter into a video-telephony session and given theuser's policy profile and/or available network resources policy server32 might determine that the user may proceed, but only with audiocapabilities.

In an embodiment of the present invention, the policy profile isrepresented as a series of Boolean expressions. The expressions may beparsed by Policy server 32 through a series of pattern matching rulessimilar to the classification rules used in token creation. Based on thepolicy profile and the contents thereof, the policy server may add,drop, or substitute tokens from the set contained in authorizationrequest 62. For example, if a user's policy profile restricts access ina particular network to audio streaming media and authorization request62 contains a video token, then policy server 32 may drop the videotoken from the set of tokens contained in authorization request 62. Oncepolicy server 32 has run through all of the Boolean expressions in thepolicy profile, the end product is a set of tokens defining the policyfor the invoked application. This set of tokens is returned toapplication server 40 and/or ACP 34 via authorize message 64.

In response to receiving authorize message 64, applications server 40,or ACP 34 in the case of SIP based applications, may continue theapplicable application invocation(s). For SIP applications, ACP 34 maydeploy the application by providing it with a set of service enablers.In a particular embodiment of the present invention, ACP may implementits own policies that govern the way a service enabler functions. Suchpolicies may be distinct from the policies of policy server 32 (to bediscussed in greater detail below). For example, the policy server mighttell ACP 34 that non-video applications of a certain bandwidth may beinvoked. In response, ACP 34 may invoke appropriate applications. Abenefit of this interdependency is that according to the availablenetwork resources and the user's policy profile totally differentapplications might be invoked. This offers a network service providergreater control over the subscriber's communication session and theapplications that run on the network.

While an authorize message implements application side policy, instructmessage 65 executes network level policy. In particular, instructmessage 65 is a communication from policy server 32 to network resourcemanager 36 indicating how network resources should be allocated for aparticular user. As an example, instruct message 65 might tell networkresource manager 36 to increase bandwidth for the call or restrictaccess to certain networks. With respect to over-the-top applications,instruct message 65 might tell the network resource manager to look forcertain types of traffic. In addition, the instruct message 65 mighttell the network resource manager how to respond to a change in networkcondition in order to eliminate superfluous communication between thenetwork resource manager and policy server. For example, the instructmessage 65 might provide that if the subscriber is in a CDMA network,then a certain bandwidth should be allocated. However, if the subscriberenters an evolution data optimized (EVDO) network, extra bandwidthshould be provided. This eliminates the process of the network resourcemanager communicating the change in networks to the policy server, thepolicy server making a policy decision, and communicating the decisionback to the network resource manager.

Inform message 66 is an interaction between network resource manager 36and policy server 32. An inform message 66 might be sent in two cases.First, when there is a change in a value of a variable corresponding toa network state that is relevant for policy server processing. Examplesof this situation might include congestion in an access gateway, firingof a counter that was configured by the policy server, or a change inthe point of attachment of a subscriber to the network. A secondsituation occurs when the user has requested an operation with respectto network resources for which authorization is required. For instance,when a user roams into a new coverage area, a decision must be made asto whether the communication session should be permitted to be handedoff. In this situation, the user requests to engage in an activity whichrequires a reallocation of network resources and, thus, approval fromthe policy server is needed. In order to provide dynamic policyenforcement, the policy server is informed when either of theabove-described situations occurs. Accordingly, inform message 66 is themeans by which the policy server becomes apprised of a change in thestatus of a network resource and/or user request.

Tell message 67 is a communication between policy server 32 and accessterminal 12. Tell message 67 might be sent by the policy server when ithas made a decision regarding an application or its usage of networkresources for which the access terminal needs to adjust its activities.For instance, a user might be running a non-SIP application and thepolicy server elects to eliminate the allocated bandwidth. In such asituation, the access terminal should be notified to provide the userwith a prompt indicating the termination of the application. Tellmessage 67 might also be sent in situations where the policy server iseither incapable or unable to make a firm decision regarding policy andrequests user input to decide. Such a situation might arise when a useris running a high bandwidth game as well as a video-telephony sessionand the network must terminate one of the applications. Accordingly, thepolicy server may tell the access terminal to provide the user with aprompt soliciting the user to select which of the applications toshutdown. It should be noted that whether or not a policy server sendstell message 67 is a matter of policy. In particular, a user's policyprofile might provide that the user should be notified prior to having acommunications session terminated.

FIG. 4 is a simplified block diagram illustrating policy peering inaccordance with an embodiment of the present invention. Policy peeringrefers to the ability of a home policy server and a policy server in avisited (e.g. roaming) network (or region) to each assert their ownpolicies for a user. A principal objective of policy peering is toprovide a seamless roaming experience for users so that a subscriberwill experience substantially the same service in networks hosted bydifferent providers, or different regions hosted by the same provider.Another objective of policy peering is to provide user-specific policydecision and enforcement while roaming. More specifically, when a useris in a roaming network, such as external MMD 26 in FIG. 1, the policyserver in the visited network does not have access to the user-specificpolicy profile as it is stored in the home network. The roaming networkprovider typically only knows that a user from a certain home networkhas entered the provider's service area. Thus, the roaming network isnot aware of the user's identity let alone the user-specific policyprofile associated with the user.

In a particular embodiment of the present invention, policy peering isimplemented by linking a policy server in the home network to a policyserver in a visited network. A particular advantage of policy peeringusing policy servers is that it enables user-specific policy to beapplied to non-SIP applications. Specifically, because policy server 32,as described above, is operable to implement policy for SIP and non-SIPapplications, linking policy servers enables roaming policy enforcementregardless of the application. Furthermore, policy peering throughpolicy servers also allows for user-specific policy to be implemented ina roaming network.

As illustrated in FIG. 4, policy server 72 and policy server 82 arelinked by connection 90. Policy servers 72 and 82 are similar topreviously referenced policy server 32. Policy server 72 is located invisited network 70 and policy server 82 is situated in home network 80.Connection 90 might be a wireless or wireline link or any other means ofconnecting devices in networks hosted by different providers. It shouldbe noted that visited network 70 and home network 80 may include anyother components, or combination devices, as may be required tofacilitate inter-network and intra-network communications and implementpolicy. In particular, it is envisioned that both visited network 70 andhome network 80 may each have policy centers 30.

When a user enters visited network 70 and executes an application, theapplication runs in home network 80 and is controlled by policy server82. Policy server 82 implements its policies as usual. However, thepolicies are a function of network state variables in visited network70. Network state variables are determined by policy server 72 based onthe status of network resources provided by network resource manager 76,which is substantially similar to network resource manager 36. Networkstate variables provide a “view” of the underlying network that aroaming network provider sends to the home network provider. Networkstate variables are not necessarily the actual state of resources (i.e.network resources) in the visited network. By contrast, they comprisevalues of resources in roaming network 70 which the roaming networkservice provider wants the home network service provider to view. Theview that is provided is a function of roaming network policy. This maybe based on the identity of the home network provider, a businessagreement between the home and roaming networks, and/or the actual stateof the network itself. Because the identity of the subscriber istypically unknown, the view is generally not a function of subscriberidentity. Further, because the applications the subscriber is runningare known and controlled by the home network, the view is generally nota function of the active applications. Once policy server 72 determinesthe applicable network state variables, it communicates them to policyserver 82 over link 90.

In response to receiving the network state variables, policy server 82implements the policy of the home network. Policy enforcement at theapplications level is similar to the standard home network policyenforcement previously described. In particular, policy server 82 mayimplement policy at the application level for SIP applications bycommunicating with application control point 84 and by directlycommunicating with application server 88 for non-SIP applications. Itshould be noted that ACP 84 is substantially similar to ACP 34 andapplication server 88 is substantially similar to application server 40.

The primary distinction between policy peering in a roaming situationand policy enforcement when a user is in a home network is with respectto network level policy enforcement. This is because the home networkservice provider does not have direct control over the resources in theroaming network. Therefore, instead of a network resource manager inhome network 80 dictating how resources should be allocated, networkresource manager 76 in the roaming network serves as the PEP for theroaming subscriber. Accordingly, home policy server 82 is viewed as anapplication by visited policy server 72. That is, home policy server 82makes requests which call for network resources and the resources areallocated between it and other applications. Thus, both the visited andhome network service providers are able to enforce their own policies.

Although the present invention has been described with particularembodiments, it should be understood that various other changes,substitutions, or modifications may be made hereto without departingfrom the spirit and scope of the present invention. For example, policycenter 30 was described with reference to a number of components. Thesecomponents may be combined, rearranged, or positioned in order toaccommodate particular routing architectures or communication needs. Inaddition, the interfacing and communication among the components may bealtered or varied without departing from the intended scope of theinvention. Accordingly, the present invention contemplates greatflexibility in the arrangement of the components of policy center 30 aswell as their interactions.

Numerous other changes, substitutions, variations, alterations, andmodifications may be ascertained by one skilled in the art and it isintended that the present invention encompass such changes, variations,alterations, and modifications as falling within the scope of theappended claims.

1. A system for enforcing policy in a communication network comprising:a policy server, the policy server operable to: receive an authorizationrequest to invoke an application; receive a policy profile for a networkuser; decide a proper allocation of network resources based on thepolicy profile, the application, application parameters, and availablenetwork resources; and communicate with a non-SIP application; a networkresource manager, the network resource manager operably associated withthe policy server, the network resource manager operable to monitoravailable network resources in the communication network, the networkresource manager further operable to allocate network resources amongsta plurality of network users; and an application control point, theapplication control point operably associated with the policy server,the application control point operable to communicate with an SIPapplication.
 2. The system of claim 1, wherein the policy server isfurther operable to: decide whether the application may be invoked basedon the application, the application parameters, the policy profile, andthe available network resources; determine a proper allocation of theavailable network resources to provide for the application; communicatea decision regarding whether the application may be invoked; andcommunicate the proper allocation of available network resources for theapplication.
 3. The system of claim 2, wherein the authorization requestcomprises at least one token representing the application.
 4. The systemof claim 2, wherein the authorization request is sent from theapplication control point, wherein the policy server is further operableto send an authorize message to the application control point, theauthorize message comprising a set of tokens indicating the properallocation of available network resources.
 5. The system of claim 2,wherein the policy server is further operable to communicate the properallocation of available network resources to the application controlpoint, wherein the authorization request to invoke an applicationrelates to a first application, wherein the application control point isoperable to initiate a second application or modify the applicationinvocation based on the proper allocation of available networkresources.
 6. The system of claim 2, wherein the policy server isoperable to invoke a non-SIP application if it decides that a non-SIPapplication may be invoked.
 7. The system of claim 2, wherein the policyserver is operable to communicate the decision regarding the properallocation of network resources to the network resource manager.
 8. Thesystem of claim 1, wherein the policy server, network resource manager,and application control point interface using DIAMETER protocol.
 9. Thesystem of claim 1, wherein the network resources comprise: quality ofservice; deep packet inspection; accounting; mobility; security;transcoding; packet replication; and relay.
 10. The system of claim 1,further comprising a deep packet inspector, the deep packet inspectoroperable to classify traffic within the communication network.
 11. Thesystem of claim 10, wherein the deep packet inspector is operable toidentify an application that operates on a server in a roaming network.12. The system of claim 1, wherein the application control point isfurther operable to transmit service enablers to SIP applications, theservice enablers containing a policy hook, the policy hook operable tocontrol the operation of the application.
 13. The system of claim 1,wherein the policy profile is a user-specific policy profile.
 14. Thesystem of claim 1, wherein the policy profile is a generic networkpolicy profile.
 15. The system of claim 1, wherein the non-SIPapplication is stored in an applications server, the application serveroperable to communicate with the policy server.
 16. The system of claim1, wherein the policy server is further operable to send a tell messageto an access terminal, the tell message indicating a change in theproper allocation of network resources.
 17. The system of claim 1,wherein the network resource manager is further operable to send aninform message in response to a change in available network resources,the inform message indicating a change in available network resources.18. A method for enforcing policy in a communication network comprising:sending a request to invoke an application from an access terminal; inresponse to receiving a request to invoke an application, sending anauthorization request for authorization to invoke to a policy server,the authorization request containing a set of tokens representing theapplication and its associated parameters; in response to receiving anauthorization request for authorization to invoke: obtaining a policyprofile; obtaining information regarding available network resourcesfrom a network resource manager; and allocating available networkresources based on the policy profile, the application, the applicationparameters, and the available network resources.
 19. The method of claim18, further comprising the steps of: determining whether an applicationmay be invoked based on the available network resources, policy profile,the application and its associated parameters; invoking the applicationin response to determining the application may be invoked.
 20. Themethod of claim 18, wherein the application is an SIP application. 21.The method of claim 18, wherein the application is a non-SIPapplication.
 22. The method of claim 18, wherein allocating availablenetwork resources further comprises deciding a proper allocation ofnetwork resources based on the policy profile, the application, and theavailable network resources and communicating the proper allocation ofnetwork resources to a network resource manager.
 23. The method of claim22, further comprising the step of sending an instruct message to anetwork resource manager communicating the proper allocation of networkresources.
 24. The method of claim 18, further comprising the step ofsending an inform message from a network resource manager in response toa change in the available network resources.
 25. The method of claim 18,further comprising the step of sending a tell message from the policyserver to the access terminal in response to a change in the properallocation of network resources.
 26. The method of claim 18, wherein thepolicy profile is access terminal specific.
 27. The method of claim 18,wherein the policy profile is generic to the communication network. 28.The method of claim 18, wherein the network resources comprise: qualityof service; deep packet inspection; accounting; mobility; security;transcoding; packet replication; and relay.
 29. A method for enforcingpolicy for a user in a visited communication network comprising:determining network state variables at a policy server in the visitedcommunication network; sending network state variables to a policyserver in a home network; sending a request for network resources to thepolicy server in the visited network based on a home network policy forthe user; and supplying network resources to the user in the visitednetwork based on the request for network resources and a visited networkpolicy.
 30. The method of claim 29, further comprising invoking anapplication in the home network based on the home network policy andnetwork state variables.
 31. The method of claim 29, wherein the homenetwork policy is user-specific.
 32. A system for enforcinguser-specific policy in a visited network comprising: a home network,the home network maintaining a user-specific policy profile; a visitednetwork having a visited network policy; a home policy server in a homenetwork operable to communicate with a non-SIP application, the homepolicy server further operable to request network resources in a visitednetwork based on the user-specific policy profile; a visited policyserver in a visited network operably associated with the policy serverin the home network, the visited policy server operable to: receive arequest for network resources from the home policy server; determinewhether to grant the request for network resources based on theavailable network resources in the visited network, the visited networkpolicy, and the request for network resources; and a network resourcemanager in the visited network, the network resource controller operableto monitor available network resources in the visited network, thenetwork resource manager further operable to allocate network resourcesamongst a plurality of users in the visited network;
 33. The system ofclaim 32, further comprising an application control point, theapplication control point operable to communicate with a SIPapplication.